The present invention relates to a choke system for a small four-cycle engine.
The choke system for a small engine has a choke plate and a choke lever for rotating the choke plate. When starting an engine, especially a cold engine, the choke lever is operated to restrict or choke off the airflow to produce a richer air-fuel mixture.
For a portable engine used in the bush cutter, hedge trimmer, blower, etc, the two-cycle engine is employed, since, the two-cycle engine is small and lightweight and has a large power compared with the same sized four-cycle engine.
In the two-cycle engine, the carburetor is provided on a side of the cylinder block as described in Japanese Utility Model Laid Open Publication 7-22054. Namely, the carburetor is disposed at a position lower than the cylinder head, and hence the choke system attached to the carburetor can also be located at a lower position. Therefore, the two-cycle engine can be designed to be small in size.
However, in recent years, demand for the four-cycle engine is rising because of the emission control.
But, in the four-cycle engine of the over head valve type, the carburetor is disposed on a side portion of the cylinder head, so that the choke system is provided at the same level of the cylinder head or a higher level than the cylinder head. As a result, the engine can not be reduced in size.
On the other hand, the choke lever is disposed on a side portion of the engine. When the choke lever is upwardly rotated, the choke plate is closed, and when downwardly operating, the choke plate is opened. This operating manner has become custom. Therefor, the operating manner must be kept.